Question:
Solve each of the following system of equations in R.
17. $\frac{2 x+1}{7 x-1}>5, \frac{x+7}{x-8}>2$
Solution:
$\frac{2 x+1}{7 x-1}>5$
$\Rightarrow \frac{2 x+1}{7 x-1}-5>0$
$\Rightarrow \frac{2 x+1-35 x+5}{7 x-1}>0$
$\Rightarrow \frac{6-33 x}{7 x-1}>0$
$\Rightarrow x \in\left(\frac{1}{7}, \frac{2}{11}\right)$ ...(i)
Also, $\frac{x+7}{x-8}>2$
$\Rightarrow \frac{x+7}{x-8}-2>0$
$\Rightarrow \frac{x+7-2 x+16}{x-8}>0$
$\Rightarrow \frac{23-x}{x-8}>0$
$\Rightarrow x \in(-\infty, 8) \cup(23, \infty) \quad \ldots \ldots($ ii $)$
Hence, the solution to the given set of inequalities is the intersection of (i) and (ii), which is empty.
$\therefore x \in \emptyset$